A156797 Numbers k such that k^2 + 2 == 0 (mod (9^2)).

22, 59, 103, 140, 184, 221, 265, 302, 346, 383, 427, 464, 508, 545, 589, 626, 670, 707, 751, 788, 832, 869, 913, 950, 994, 1031, 1075, 1112, 1156, 1193, 1237, 1274, 1318, 1355, 1399, 1436, 1480, 1517, 1561, 1598, 1642, 1679, 1723, 1760, 1804, 1841, 1885

Offset

1,1

Comments

Numbers k such that k mod 81 is 22 or 59. - Charles R Greathouse IV, Dec 23 2011

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (1,1,-1).

Formula

Sum_{n>=1} (-1)^(n+1)/a(n) = tan(37*Pi/162)*Pi/81. - Amiram Eldar, Feb 26 2023

Mathematica

Select[Range[2000], PowerMod[#, 2, 81]==79&] (* Harvey P. Dale, Jun 30 2011 *)
LinearRecurrence[{1, 1, -1}, {22, 59, 103}, 50] (* Vincenzo Librandi, Feb 09 2012 *)

Prog

(PARI) a(n)=n\2*81-22*(-1)^n \\ Charles R Greathouse IV, Dec 23 2011
(Magma) I:=[22, 59, 103]; [n le 3 select I[n] else Self(n-1)+Self(n-2)-Self(n-3): n in [1..50]]; // Vincenzo Librandi, Feb 09 2012

Crossrefs

Sequence in context: A202387 A044124 A044505 * A216299 A255431 A221595

Adjacent sequences: A156794 A156795 A156796 * A156798 A156799 A156800

Keyword

nonn,easy

Author

Vincenzo Librandi, Feb 16 2009

Status

approved